PROJECT SUMMARY Inferring the demographic history of a population is an important task in population genetics. Although several methods are available for this task, how to take advantage of large sample size of whole genome sequence data and provide accurate estimation of demographic history remains an open question. We propose several approaches to overcome the shortcomings of existing methods and specifically improve their accuracy and scalability for large sample size and whole genome sequence data. The resulting methods will be applied to the whole genome sequences of the genotype-rich human populations such as the TOPMED European American cohorts (~30,000 individuals) and Icelander whole genome sequence data (2,636 individuals), and provide good estimation of the demographic histories. Finally, a software package will be developed to incorporate the new methods and assist other researchers to easily apply the method to their own data.